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A Bottom-Following Preview Controller for
Autonomous Underwater Vehicles
Carlos Silvestre, Rita Cunha, Nuno Paulino, and António Pascoal
By:
Ahmed El Sheikh
MSc Student, Mechatronics and Robotics, Sghool of Innovative Design, E-JUST
[email protected]
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Carlos Silvestre: PhD, (IST), Lisbon,
Portugal.
Rita Cunha: PhD, (IST), Lisbon,
Portugal.
Nuno Paulino: M.Sc, (IST),
Lisbon, Portugal.
António M. Pascoal, PhD,
(IST), Lisbon, Portugal
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Overview
• State of The Art
• Vehicle Dynamics
• Error Space
• Preview Problem Formulation• Preview Problem Formulation
• Discrete Time Controller Design
• Reference Path
• Implementation
• Simulation Results
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State of The Art
• Solving the problem of bottom –following for AUV
• Using the echo sounders to evaluate the terrain
characteristics
• AUV linearized error dynamics for a pre-defined set of
operating regionsoperating regions
• Using the LMIs to solve the H2 state feedback control
problem
• Using the D-Methodology to implement non-linear
controller.
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Vehicle Dynamics
INFANTE vehicle
Vehicle Characteristics
Length(m) 4.5
Width(m) 1.1
Height(m) 0.6
Thrusters 2 (Propellers & Nozzles)
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Vehicle Dynamics(cont’)
Coordinate frames: inertial {I}, Body {B}
Serret {T}, Desired Body {C}
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Error Space
The vector of control inputs is:
And the output vector is:
Assume straight line, Vr=qc=0,
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Error Space(cont’)
Error linearization
Discretization
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Preview Problem Formulation
Reference path—slope discontinuityTwo echo sounders are used to
measure the characteristics of the
seabed ahead of the AUV.
The linear error dynamics
The seabed signal
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Preview Problem Formulation(cont’)
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Discrete Time Controller Design
The Linear Matrix Inequalities
(LMIs)approach is used to
design the discrete time H2
state feedback controller
Theoretical Background
Feedback interconnection
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Discrete Time Controller Design(cont’)
Preview Controller Synthesis Technique
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Reference PathSensor readings &offset to obtain the data points
•Adding the elevation offset
•Output inertial frame {I} - x coordinate
•Points- straight lines
Final computed path (segments of straight lines)
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Implementation Operating regions parameterized byAffine Parameter-Dependent Description of
The plant
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Implementation (cont’)Implementation setup using gain scheduling and the D-methodology
D- Methodology
•Integrators (input)
•Differentiator (needed
•Stability Characteristics
•Linearization•Linearization
•Auto trimming Property
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Implementation (cont’)Evolution of the preview gains f(t)
Closed-loop system’s H2 norm
Trajectories described by the vehicle
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Simulation Results
The control objective is to achieve a constant 15-mbottom elevation offset.
Descending phase Climbing phase.
Error vector Xe (t)
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The Papers I’ve presented
The PapersPaper 1 A SURVEY OF UNDERWATER VEHICLE
NAVIGATION: RECENT ADVANCES AND
NEW CHALLENGES
Published
Paper 2 An Adaptive Controller for Underwater Vehicle-Manipulator Systems Including
Thruster DynamicsThruster Dynamics
Published Proceedings of the 2010 International Conference on
Modeling, Identification and Control, Okayama, Japan, July 17-19,2010
Paper 3 A Bottom-Following Preview Controller for
Autonomous Underwater Vehicles
Published IEEE TRANSACTIONS ON CONTROL SYSTEMS TECHNOLOGY, VOL. 17, NO. 2,
MARCH 2009